Wind Advisory 4, NWS Sacramento, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
345 PM PST MON JAN 18 2010

.DISCUSSION...
200+ KT ZONAL JET STREAM CENTERED OVER THE CENTRAL PACIFIC AROUND
40N CONTINUES TO BE THE DRIVING FORCE FOR NORTHERN CALIFORNIA
WEATHER. WATER VAPOR IMAGERY SHOWS THE NEXT FRONTAL SYSTEM IN A
SERIES OF QUICK MOVING STORMS HAVING JUST SWEPT THROUGH NORTHERN
CALIFORNIA. THIS STORM...WITH THE SUPPORT OF THE LEFT EXIT QUADRANT
OF THE UPPER JET...CONTINUES TO BRING A FAIR AMOUNT OF WEATHER TO
THE FORECAST AREA. VALLEY RAINFALL TOTALS HAVE MEASURED ANYWHERE
FROM ABOUT A QUARTER OF AN INCH IN THE NORTHERN SAN JOAQUIN
VALLEY...AROUND HALF AN INCH IN THE SACRAMENTO VALLEY...AND AN INCH
OR GREATER TO FOOTHILL AND MOUNTAIN LOCATIONS. AHEAD OF THE
FRONT...GUSTY WINDS WERE ALSO FELT. OROVILLE REPORTED A PEAK WIND
GUST OF 63 MPH SHORTLY AFTER NOON AND SAC INTL HAD A GUST OF 51 MPH.
BEHIND THE FRONT...PARTIAL CLEARING COUPLED WITH DECENT MID-LEVEL
INSTABILITY TO GENERATE SHOWERS AND THUNDERSTORMS. SOME OF THESE
THUNDERSTORMS ALONG THE SIERRA ARE CAPABLE OF GENERATING VERY GUSTY
WINDS AND SMALL HAIL.

CONTINUE TO SEE HEAVY SNOWFALL ABOVE THE MOUNTAINS. THE HIGHEST
TOTAL REPORTED THUS FAR HAS BEEN NEAR KIRKWOOD...WHICH SAW 10
INCHES OF SNOW FALL YESTERDAY AN ADDITIONAL 7 INCHES THUS FAR AS OF
2PM...WITH HEAVY SNOWFALL CONTINUING.

A FEW MORE HOURS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
THROUGH THIS EVENING BEFORE THE SUN SETS AND WE LOSE SURFACE
HEATING. SHOWERS WILL GRADUALLY TAPER OFF INITIALLY AT LOWER
ELEVATIONS AND THEN TOWARDS THE MOUNTAINS LATE TONIGHT. THIS
RELATIVE LULL WILL BE SHORT-LIVED HOWEVER AS THE NEXT STORM SYSTEM
(THE THIRD IN A TRAIN OF FIVE) ARRIVES TUESDAY.

THE TUESDAY STORM LOOKS SLIGHTLY LESS IMPRESSIVE THAN TODAYS STORM.
FORECAST QPFS ARE GENERALLY LESS...AND SURFACE GRADIENTS SHOULD BE A
TAD WEAKER THOUGH IT SHOULD STILL BE BREEZY. HAVE OPTED TO ISSUE
SNOW ADVISORIES FOR THE MOUNTAINS FOR THIS TIME PERIOD TO REFLECT
THE FORECAST SLOWER SNOW ACCUMULATIONS.

THE FOURTH STORM ARRIVES WEDNESDAY...WHICH LOOKS TO BE ABOUT AS
STRONG TO SLIGHTLY STRONGER THAN TODAYS. AS SUCH...CAN PROBABLY
EXPECT SIMILAR WEATHER CONDITIONS THEN. THE FIFTH IN THE SERIES WILL
ARRIVE IN NORTHERN CALIFORNIA THURSDAY. THIS LAST STORM WILL BE
SLIGHTLY DIFFERENT THAN THE REST IN THAT IT WILL LIKELY BE A CLOSED
UPPER LOW THAT MOVES INLAND...THUS SETTING THE STAGE FOR A MORE
CONVECTIVE / SHOWERY EVENT. DANG

&&

.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)...
THE WET PATTERN CONTINUES ON FRIDAY WITH A BROAD TROUGH OVER THE
REGION. THE HEAVIEST PRECIPITATION LOOKS LIKE IT WILL BE OVER
SOUTHERN CALIFORNIA...BUT ALSO EXPECT SIGNIFICANT VALLEY RAIN AND
MOUNTAIN SNOW OVER NORTHERN CALIFORNIA BEFORE THIS SYSTEM EXITS.
SNOW LEVELS WILL BE QUITE LOW AT 3000-3500 FEET WITH 700 MB
TEMPERATURES AROUND -10 C AND THICKNESSES AT 535 DAM. GUSTY WINDS
MAY BRING DOWN TREES IN WELL SATURATED SOILS AND LOCAL STREAM
FLOODING IS A POSSIBILITY. EXTENDED MODELS SUGGESTING A BREAK IN THE
STORMY PATTERN WITH UPPER LEVEL RIDGING DEVELOPING FOR THE WEEKEND.
THE TIMING OF THIS RIDGING IS UNCERTAIN...BUT COULD BRING WARMER AND
SOMEWHAT DRIER WEATHER AFTER A VERY WET WEEK. THIS COULD BE FAIRLY
DIRTY RIDGING...SO SOME SHOWERS ARE STILL A POSSIBILITY. THE
ECMWF...GFS AND GEM ALL POINT TOWARDS A DEEP LOW APPROACHING LATE
SUNDAY INTO MONDAY...WHICH WOULD BRING RENEWED STORMY WEATHER TO THE
AREA.

&&

.AVIATION DISCUSSION...
PAC FNTL SYS MOVG THRU CWA ATTM WITH NXT SYS MOVG INLD TUE MRNG. FOR
CNTRL VLY...IMPVG CONDS THIS EVE WITH SCT MVFR POSS IN -SHRA. ISOLD
-TSRA POSS TIL 04Z TUE. WDSPRD SLY SFC WND GSTS 25-35 KTS TIL 05Z.
CONDS DTRTG AFT 12Z TUE AGN AS NXT SYS MOVS INLD. FOR CSTL AND NRN
INTR MTNS...WDSPRD IFR WITH LCL LIFR CONDS TIL 03Z THEN IMPVG OVNGT
THEN CONDS DTRTG AGN AFT 10Z TUE. ISOLD -TSRA POSS TIL 04Z. SN LVLS
ARND 040-050 AMSL. AREAS SLY SFC WND GSTS 30-40 KTS OMTNS. FOR
SIERNEV...WDSPRD IFR/LIFR CONDS WITH SN LVLS ARND 040-050 AMSL.
ISOLD -TSRA OR -TSSN POSS TIL 05Z. AREAS S-SW SFC WND GSTS 35-45 KTS
OR GTR OVR HYR TRRN.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 4 AM PST TUESDAY FOR WEST SLOPE NORTHERN
SIERRA NEVADA-WESTERN PLUMAS COUNTY/LASSEN PARK.

WIND ADVISORY UNTIL 6 PM THIS EVENING FOR THE SACRAMENTO
VALLEY...DELTA...NORTHERN SAN JOAQUIN VALLEY AND SOUTHERN LAKE
COUNTY.

WINTER WEATHER ADVISORY UNTIL 4 PM PST TUESDAY FOR MOUNTAINS
SOUTHWESTERN SHASTA COUNTY TO NORTHERN LAKE COUNTY-SHASTA LAKE AREA/
NORTHERN SHASTA COUNTY/BURNEY BASIN-EASTERN SHASTA COUNTY.

WINTER WEATHER ADVISORY FROM 10 AM TUESDAY TO MIDNIGHT PST TUESDAY
NIGHT FOR WEST SLOPE NORTHERN SIERRA NEVADA-WESTERN PLUMAS
COUNTY/LASSEN PARK.

&&